The RMT union's complaints relate to the transfer of Piccadilly Line control-room services to a new centre in Hammersmith.
Transport for London plans to replace a number of separate control centres with a single one from 2017.
The Rail, Maritime and Transport Union says the move will cause job losses - and that there are also issues with rates of pay and the lack of "any meaningful offer for Service Control staff for the Olympic period."
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The venue says it is in contact with promoters about a final decision, following the terror attack at the singer's concert on Monday.
Soldiers will replace armed police at many sites after security experts warned the Government that another terrorist attack may be imminent.
The threat level has been raised to critical by MI5's Counter-Terrorism Analysis Centre.